Shaun Edwards will know the intricacies of Wales defensive structures better than anyone, but the majority of the time, the blitz defence is led from the 13 channel.

But Roberts isn’t concerned and revealed that he didn’t enjoy trying to get hold of the 22-year-old when Racing Metro hosted Northampton in the European Champions Cup.

“We’ve played together before, against France, and we’ve covered a lot of defensive things in training,” he explained.

“The important thing this Saturday against Australia is starter plays. Whether it’s off the top ball or from the scrum, they like to have a crack at you from first phase and they’re very good at doing it.

“They’ve cut the best sides in the world apart numerous times this season, so our set-piece defence certainly has to be on the money this week.”

Roberts added: “We’ve worked on it hard and George has played there a few times for his club this season.

“I played against him for Racing a few weeks ago and he played most of the second half at 13. He’s quite scary to mark, I can tell you that.”

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Roberts was involved when Wales last beat Australia in 2008, when he fractured his skull in a thunderous collision with Sterling Mortlock in the third minute.

The Racing Metro centre revealed that training has been of particularly high intensity in an attempt to replicate how it will feel for the players against ‘the big three’.

“We’ve done a lot of fitness work, making sure that we’re making good decisions when we’re fatigued and replicating what it’s going to be like on Saturday,” he said.

“It’s been tough, we’ve been training at a high intensity and it’s been spoken about a lot this week, the jump from club rugby to international rugby and certainly against the southern hemisphere teams.

The 27-year-old added: “They play at a pace which is not what we’re used to up here.

“We’ve tried to replicate that in training, so the boys won’t be too surprised come Saturday.”

While Roberts will spend the majority of his time on Saturday trying to blow a hole in the Australian midfield, he targeted the breakdown as a real area of importance this weekend.

“It’s hard to read too much into their game against the Barbarians last weekend, when you play the Baa-Baas it’s always a very different game to any other Test match,” he said.

“We know how Australia are going to play, Michael Chieka has been successful wherever he has coached previously and we know his style of play.

“The Waratahs play with tempo, they love having speed on the ball and that contact area is going to be crucial on Saturday.”